As a refrigerator, a turbo refrigerator, which is provided with a turbo compressor which compresses a refrigerant by rotating an impeller by a motor and discharges the compressed refrigerant, is known. The turbo compressor is assembled by connecting a compressor casing which accommodates the impeller, and a motor casing which accommodates the motor.
Patent Document 1 discloses a structure of connecting a compressor casing and a motor casing. The motor casing has a main body part formed in a cylindrical shape, and a mounting flange extending in a radial direction from the main body part. A mounting flange having the same diameter as the mounting flange of the motor casing is provided in the compressor casing, and both the mounting flanges are connected by a connecting bolt, whereby a turbo compressor is assembled (refer to FIG. 2 of Patent Document 1).